In order to explore the characteristics and influence factors of atmospheric boundary layer inversion in Yinchuan City and their relationship with winter PM_2.5 pollution, based on the sounding and surface meteorological observation data at Yinchuan meteorological station and the air quality monitoring data in Yinchuan City from 2015 to 2020, the characteristics of atmospheric boundary layer inversion and surface meteorological elements are analyzed. And on this basis that the influence of inversion and surface meteorological elements on PM_2.5 pollution weathers in winter is explored. The results are as follows: (1) The inversions in atmospheric boundary layer are more easily to occur in the early morning than in the evening in Yinchuan City, and most of the inversions are ground inversions, they are stronger and thinner than suspension inversions. The inversion frequency and thickness are the largest in winter and the smallest in summer, while the inversion intensity is the strongest in autumn and the weakest in summer. (2) In winter, the inversions are easily to occur on a sunny day with average surface wind speed from 1.0 to 1.5 m·s^-1 and relative humidity from 30% to 60%. (3) Ground inversion is one of the main meteorological factors affecting PM_2.5 pollution weathers in winter. When the inversion thickness exceeds 596 m and the intensity exceeds 1.4 ℃·(100 m)^-1, PM_2.5 pollution weathers are easily to occur, and the pollution is aggravated with the increase of inversion thickness and intensity. (4) Under PM_2.5 pollution weathers in winter, the sky is mostly sunny in the early morning, the average surface wind speed is usually less than 1.3 m·s^-1, the relative humidity is greater than 54%, and the pollution is aggravated with the increase of humidity. (5) The boundary layer height is significantly negatively correlated with PM_2.5 mass concentration, and the lower boundary layer height is, the heavier PM_2.5 pollution is.

 Weather radar is an atmospheric remote sensing detection equipment used to detect weather phenomena and meteorological elements in the atmosphere. The study of radar climatology can help us understand the temporal and spatial distribution and evolution characteristics of convective storms and convective precipitation, as well as the occurrence frequency and storm properties of strong weather. The new progresses were reviewed as follows: (1) The research progress of radar climatology of convective storms mainly revealed the daily cycle and spatial variation characteristics of convection, and analyzed the relationship between the formation, strengthening and characteristics of the daily cycle of convection and solar radiation heating, topography and mesoscale system activities. (2) The research of radar precipitation climatology mainly focused on the characteristics of precipitation in different regions, the characteristics of different types of precipitation systems, and the application of composite radar precipitation data, including the improvement of radar precipitation data retrieval algorithms. (3) Studies on 3D storm tracking method were introduced, including the classification of storms according to different storm tracks and attributes and differences in the initiation and development mechanism of different kinds of storms.

In order to explore the impact of urban canopy effect on forecast of surface meteorological element, the optimized urban single model was coupled into the rapid-refresh multi-scale analysis and prediction system-short term (RMAPS-ST). For this purpose, two contrast experiments were set, they were the coupling urban single model or uncoupling urban single model into the RMAPS-ST denoted as UCM and NOUCM, respectively. In addition, the short-term forecast effects of surface meteorological elements (2 m temperature, 10 m wind speed and 2 m specific humidity) in North China were evaluated in mid-January and mid-July 2017. The results show that UCM test could significantly improve the forecast performance of the RMAPS-ST to surface meteorological elements. Compared with NOUCM test, the prediction of surface meteorological elements in UCM test was closer to the observation in cities of North China. Considering canopy effect could effectively reduce forecast bias of 2 m temperature in most urban stations of North China, and the accuracy of 24-hour temperature forecast improved by 42% and 15% in mid-January and mid-July, respectively. The urban canopy effect could increase friction coefficients, which decreased low-level wind speed significantly and improved the prediction ability of 10 m wind speed, and the forecast accuracy improved by 40% and above. For specific humidity at 2 meters height, the impact of canopy effect on the forecast of specific humidity wasn’t significant. Compared with the observation, the forecasted specific humidity at 2 meters height by two tests was dryer in all day in mid-July, and the canopy effect could significantly improve dryer state in urban areas, the forecast accuracy increased by 17%.

Based on precipitation data and traffic accident data provided by Hainan traffic management departments on G98 highway around Hainan island from 2010 to 2014, the distribution characteristics of expressway traffic accidents around  Hainan island were analyzed. It was found that heavy rainfall was the most catastrophic weather that induced traffic accidents. The grey correlation method was used to evaluate and analyze the traffic accidents caused by heavy rainfall. Based on three evaluation indexes including death toll, injury toll and direct economic property loss, the grey correlation degrees order of 40 typical traffic accident cases were obtained. The accumulated rainfall days, maximum daily rainfall and maximum hourly rainfall as hazard index of hazard formative factor, the high-risk road of heavy rainfall, single vehicle flow as fragility indexes of disaster-bearing bodies, the traffic accident frequency caused by rainfall and maximum grey correlation degree of accidents as vulnerability indexes of disaster-bearing bodies, the model of risk zoning index of heavy rainfall meteorological disasters around the island was constructed. Then the risk zoning indexes of 11 management stations were caculated, and spatial distribution of risk zoning around Hainan island was also obtained. It was pointed out that the road from Ding’an to Wanning was the high risk section under heavy rainfall weather condition, which should be paid more attention in traffic  meteorological service.